function changeStyle(title) {
    var i, a, main;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
        if (a.getAttribute("rel").indexOf("Style") != -1 && a.getAttribute("title")) {
            a.disabled = true;
            if (a.getAttribute("title") == title) {
                a.disabled = false;
            }
        }
    }

}

function getActiveStyleSheet() {
    var i, a;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
        if (a.getAttribute("rel").indexOf("Style") != -1 && a.getAttribute("title") && !a.disabled)     return a.getAttribute("title");
    }
}

function getPreferredStyleSheet() {
    var i, a;
    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
        if (a.getAttribute("rel").indexOf("Style") != -1
       && a.getAttribute("rel").indexOf("alt") == -1
       && a.getAttribute("title")
       ) return a.getAttribute("title");
    }
    return null;
}

function createCookie(name, value, days) {
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        var expires = "; expires=" + date.toGMTString();
    }
    else expires = "";
    document.cookie = name + "=" + value + expires + "; path=/";
}

window.onload = function(e) {

    var cookie = getCookie("Style");
    var title = cookie ? cookie : getPreferredStyleSheet();
    changeStyle(title);
}

window.onunload = function(e) {
    var title = getActiveStyleSheet();
    createCookie("Style", title, 1);
}

var cookie = getCookie("Style");
var title = cookie ? cookie : getPreferredStyleSheet();
changeStyle(title);